Data recording device, data recording method, data editing device, and data editing method

ABSTRACT

An original coded stream reproduced from a magnetic tape is decoded by an MPEG decoder, and original video data of a base band is thus generated. A switching circuit generates edited video data by switching the original video data and supplied insertion video data on the base band level at IN-point and OUT-point. The MPEG encoder generates an edited coded stream by coding the edited video data supplied from the switching circuit. A system controller controls a recording circuit to record a picture changed by editing processing, from among the edited coded stream, onto the magnetic tape.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 09/331,807, filed Aug. 10, 1999 now U.S. Pat. No. 6,782,188.

TECHNICAL FIELD

This invention relates to a data recording device and a data recordingmethod for editing, for each frame, a bidirectionally predictive codedstream based on the MPEG2 (Moving Picture Experts Group Phase 2)standard, and a data editing device and a data editing method whichenable insertion editing for each frame.

BACKGROUND ART

Recently, there is proposed a digital video tape recorder forcompression-coding video data by using a compression coding techniquesuch as MPEG2 and recording the compression-coded stream onto a magnetictape.

In accordance with the MPEG2 standard, a bidirectionally predictivecoding system is employed as the coding system. In this bidirectionallypredictive coding system, three types of coding, that is, intra-framecoding, inter-frame forward predictive coding, and bidirectionallypredictive coding, are carried out. Pictures of the respective types arereferred to as I-picture (intra coded picture), P-picture (predictivecoded picture), and B-picture (bidirectionally predictive codedpicture).

In general, I-picture, obtained by intra-frame coding, is not a picturepredictively coded from another picture but a picture singly codedwithin this picture. P-picture, obtained by inter-frame forwardpredictive coding, is a picture predictively coded from past I-pictureor P-picture. B-picture, obtained by bidirectionally predictive coding,is a picture bidirectionally predicted from past I-picture or P-pictureand future I-picture or P-picture.

Also, in accordance with the MPEG standard, it is prescribed that anI-picture should be periodically inserted to enable random access. Theunit thereof is referred to as GOP (Group Of Pictures).

At broadcasting stations, editing processing for editing a plurality oforiginal video materials recorded on magnetic tapes so as to produce atelevision program to be on the air is carried out. In the case wheresuch editing processing is carried out, edit points such as IN-point andOUT-point are set on the frame basis, and the plurality of videomaterials are cut and connected on the basis of the set edit points.

However, P-picture and B-picture included in a coded stream inconformity to the MPEG standard are pictures predictively coded from apast picture or a future picture, and are closely interrelated with thepast or future picture. Therefore, a problem arises such that the codedstream cannot be cut or connected at an arbitrary frame position on thestream.

For example, if two different coded streams are forcedly connected witheach other at an edit point, the picture quality of a decoded image isconsiderably deteriorated because a predictive picture of a picture nearthe editing point differs from a picture at the time of coding. Also, insome cases, since the coding parameter becomes discontinuous at the editpoint, decoding cannot be carried out.

In short, in the conventional digital video tape recorder for recordinga coded stream which is compression-coded in accordance with the MPEGstandard, it is difficult to edit a coded stream recorded on a magnetictape on the frame basis (picture basis). In addition, in theconventional digital video tape recorder in accordance with the MPEGstandard, it is difficult to edit a coded stream recorded on a magnetictape without deteriorating the picture quality.

DISCLOSURE OF THE INVENTION

In view of the foregoing status of the art, it is an object of thepresent invention to provide a data recording device and a datarecording method for editing, on the frame basis, a coded streambidirectionally predictive coded in accordance with the MPEG standard,and a data editing device and a data editing method which enableinsertion editing on the frame basis. It is another object of thepresent invention to provide an editing device and an editing method inwhich the picture quality of a coded stream processed by insertionediting is not deteriorated.

A data recording device according to the present invention includes:reproducing means for reproducing an original coded stream recorded on arecording medium; decoding means for decoding the original coded streamoutputted from the reproducing means, thereby generating decoded videodata of a base band; editing means for switching the decoded video dataof the base band and insertion video data at a set edit point, therebygenerating edited video data of the base band; coding means for codingthe edited video data to generate an edited coded stream; recordingmeans for recording the edited coded stream onto the recording medium;and control means for controlling the recording means to record apicture corresponding to the insertion video data and a picture near theedit point, from among the edited coded stream, at positionscorresponding to pictures of the original coded stream recorded on therecording medium.

Also, a data recording device according to the present inventionincludes: reproducing means for reproducing an original coded streamrecorded on a recording medium; decoding means for decoding the originalcoded stream outputted from the reproducing means, thereby generatingdecoded video data of a base band; editing means for switching thedecoded video data of the base band and insertion video data at a setedit point, thereby generating edited video data; coding means forcoding the edited video data to generate an edited coded stream;recording means for recording the edited coded stream onto the recordingmedium; and control means for controlling the recording means to recorda picture of the edited coded stream onto the recording medium byoverwriting in the case where the picture of the edited coded stream isaffected by editing processing by the editing means and is differentfrom a picture of the original coded stream recorded on the recordingmedium, and not to record the picture of the edited coded stream ontothe recording medium in the case where the picture of the edited codedstream is not affected by editing processing by the editing means and isthe same as the picture of the original coded stream recorded on therecording medium.

Also, a data recording device according to the present inventionincludes: reproducing means for reproducing an original coded streamrecorded on a recording medium; decoding means for decoding the originalcoded stream outputted from the reproducing means, thereby generatingdecoded video data of a base band; editing means for switching thedecoded video data and insertion video data on the base band level at anedit point, thereby generating edited video data; coding means forencoding the edited video data, the coding means encoding a picture nearIN-point and a picture near OUT-point so that the coded stream becomescontinuous at the IN-point and OUT-point; recording means for recordingthe edited coded stream onto the recording medium; and control means forcontrolling the recording means to record only a picture of the editedcoded stream affected by editing processing by the editing means, ontothe recording medium.

Also, a data recording device according to the present inventionincludes: reproducing means for reproducing an original coded streamrecorded on a recording medium; decoding means for decoding the originalcoded stream outputted from the reproducing means, thereby generatingdecoded video data of a base band; editing means for switching thedecoded video data of the base band and insertion video data at a setedit point, thereby generating edited video data; coding means forcoding the edited video data to generate an edited coded stream;recording means for recording the edited coded stream onto the recordingmedium; and control means for controlling the recording means to recordpictures from a picture immediately after IN-point onto the recordingmedium by overwriting in the case where a picture immediately before theIN-point is I-picture, and controlling the recording means to recordpictures at least from B-picture as a picture immediately before theIN-point onto the recording medium by overwriting in the case where thepicture immediately before the IN-point is B-picture.

A data recording method according to the present invention includes thesteps of: reproducing an original coded stream recorded on a recordingmedium; decoding the reproduced original coded stream, therebygenerating decoded video data of a base band; switching the decodedvideo data of the base band and insertion video data at a set editpoint, thereby generating edited video data of the base band; coding theedited video data to generate an edited coded stream; and recording apicture corresponding to the insertion video data and a picture near theedit point, from among the edited coded stream, at positionscorresponding to pictures of the original coded stream recorded on therecording medium.

Also, a data recording method according to the present inventionincludes the steps of: reproducing an original coded stream recorded ona recording medium; decoding the reproduced original coded stream,thereby generating decoded video data of a base band; switching thedecoded video data of the base band and insertion video data at a setedit point, thereby generating edited video data; coding the editedvideo data to generate an edited coded stream; and recording a pictureof the edited coded stream onto the recording medium by overwriting inthe case where the picture of the edited coded stream is affected byediting processing and is different from a picture of the original codedstream recorded on the recording medium, while not recording the pictureof the edited coded stream onto the recording medium in the case wherethe picture of the edited coded stream is not affected by editingprocessing and is the same as the picture of the original coded streamrecorded on the recording medium.

Also, a data recording method according to the present inventionincludes: a step of reproducing an original coded stream recorded on arecording medium; a step of decoding the reproduced original codedstream, thereby generating decoded video data of a base band; a step ofswitching the decoded video data and insertion video data on the baseband level at an edit point, thereby generating edited video data; acoding step of encoding the edited video data, for encoding a picturenear IN-point and a picture near OUT-point so that the coded streambecomes continuous at the IN-point and OUT-point; a recording step ofrecording the edited coded stream onto the recording medium; and acontrol step of controlling the recording step to record only a pictureof the edited coded stream affected by editing processing at the editingstep, onto the recording medium.

Also, a data recording method according to the present inventionincludes: a reproducing step of reproducing an original coded streamrecorded on a recording medium; a decoding step of decoding the originalcoded stream outputted from the reproducing step, thereby generatingdecoded video data of a base band; an editing step of switching thedecoded video data of the base band and insertion video data at a setedit point, thereby generating edited video data; a coding step ofcoding the edited video data to generate an edited coded stream; arecording step of recording the edited coded stream onto the recordingmedium; and a control step of controlling the recording step to recordpictures from a picture immediately after IN-point onto the recordingmedium by overwriting in the case where a picture immediately before theIN-point is I-picture, and controlling the recording step to recordpictures at least from B-picture as a picture immediately before theIN-point onto the recording medium by overwriting in the case where thepicture immediately before the IN-point is B-picture.

A data editing device according to the present invention includes:reproducing means for reproducing an original coded stream recorded on arecording medium; decoding means for decoding the original coded streamoutputted from the reproducing means, thereby generating decoded videodata of a base band; editing means for switching the decoded video dataof the base band and insertion video data at a set edit point, therebygenerating edited video data of the base band; coding means for codingthe edited video data to generate an edited coded stream; recordingmeans for recording the edited coded stream onto the recording medium;and control means for realizing insertion editing on the frame basis bycontrolling the recording means to record a picture corresponding to theinsertion video data and a picture near the edit point, from among theedited coded stream, at positions corresponding to pictures of theoriginal coded stream recorded on the recording medium.

Also, a data editing device according to the present invention includes:reproducing means for reproducing an original coded stream recorded on arecording medium; decoding means for decoding the original coded streamoutputted from the reproducing means, thereby generating decoded videodata of a base band; editing means for switching the decoded video dataof the base band and insertion video data at a set edit point, therebygenerating edited video data; coding means for coding the edited videodata to generate an edited coded stream; recording means for recordingthe edited coded stream onto the recording medium; and control means forcontrolling the recording means to record a picture of the edited codedstream onto the recording medium by overwriting in the case where thepicture of the edited coded stream is affected by editing processing bythe editing means and is different from a picture of the original codedstream recorded on the recording medium, and not to record the pictureof the edited coded stream onto the recording medium in the case wherethe picture of the edited coded stream is not affected by editingprocessing by the editing means and is the same as the picture of theoriginal coded stream recorded on the recording medium.

Also, a data editing device according to the present invention includes:reproducing means for reproducing an original coded stream recorded on arecording medium; decoding means for decoding the original coded streamoutputted from the reproducing means, thereby generating decoded videodata of a base band; editing means for switching the decoded video dataand insertion video data on the base band level at an edit point,thereby generating edited video data; coding means for encoding theedited video data, the coding means encoding a picture near IN-point anda picture near OUT-point so that the coded stream becomes continuous atthe IN-point and OUT-point; recording means for recording the editedcoded stream onto the recording medium; and control means for enablinginsertion editing on the frame basis by controlling the recording meansto record only a picture of the edited coded stream affected by editingprocessing by the editing means, onto the recording medium.

Also, a data editing device according to the present invention includes:reproducing means for reproducing an original coded stream recorded on arecording medium; decoding means for decoding the original coded streamoutputted from the reproducing means, thereby generating decoded videodata of a base band; editing means for switching the decoded video dataof the base band and insertion video data at a set edit point, therebygenerating edited video data; coding means for coding the edited videodata to generate an edited coded stream; recording means for recordingthe edited coded stream onto the recording medium; and control means forcontrolling the recording means to record pictures from a pictureimmediately after IN-point onto the recording medium by overwriting inthe case where a picture immediately before the IN-point is I-picture,and controlling the recording means to record pictures at least fromB-picture as a picture immediately before the IN-point onto therecording medium by overwriting in the case where the pictureimmediately before the IN-point is B-picture.

A data editing method according to the present invention includes thesteps of: reproducing an original coded stream recorded on a recordingmedium; decoding the reproduced original coded stream, therebygenerating decoded video data of a base band; switching the decodedvideo data of the base band and insertion video data at a set editpoint, thereby generating edited video data of the base band; coding theedited video data to generate an edited coded stream; and enablinginsertion editing on the frame basis by recording a picturecorresponding to the insertion video data and a picture near the editpoint, from among the edited coded stream, at positions corresponding topictures of the original coded stream recorded on the recording medium.

Also, a data editing method according to the present invention includesthe steps of: reproducing an original coded stream recorded on arecording medium; decoding the reproduced original coded stream, therebygenerating decoded video data of a base band; switching the decodedvideo data of the base band and insertion video data at a set editpoint, thereby generating edited video data; coding the edited videodata to generate an edited coded stream; and recording a picture of theedited coded stream onto the recording medium by overwriting in the casewhere the picture of the edited coded stream is affected by editingprocessing and is different from a picture of the original coded streamrecorded on the recording medium, while not recording the picture of theedited coded stream onto the recording medium in the case where thepicture of the edited coded stream is not affected by editing processingand is the same as the picture of the original coded stream recorded onthe recording medium.

Also, a data editing method according to the present invention includes:a step of reproducing an original coded stream recorded on a recordingmedium; a step of decoding the reproduced original coded stream, therebygenerating decoded video data of a base band; a step of switching thedecoded video data and insertion video data on the base band level at anedit point, thereby generating edited video data; a coding step ofencoding the edited video data, for encoding a picture near IN-point anda picture near OUT-point so that the coded stream becomes continuous atthe IN-point and OUT-point; a recording step of recording the editedcoded stream onto the recording medium; and a control step ofcontrolling the recording step to record only a picture of the editedcoded stream affected by editing processing, onto the recording medium,thereby enabling insertion editing on the frame basis.

Also, a data editing method according to the present invention includes:a reproducing step of reproducing an original coded stream recorded on arecording medium; a decoding step of decoding the original coded streamoutputted from the reproducing step, thereby generating decoded videodata of a base band; an editing step of switching the decoded video dataof the base band and insertion video data at a set edit point, therebygenerating edited video data; a coding step of coding the edited videodata to generate an edited coded stream; a recording step of recordingthe edited coded stream onto the recording medium; and a control step ofcontrolling the recording step to record pictures from a pictureimmediately after IN-point onto the recording medium by overwriting inthe case where a picture immediately before the IN-point is I-picture,and controlling the recording step to record pictures at least fromB-picture as a picture immediately before the IN-point onto therecording medium by overwriting in the case where the pictureimmediately before the IN-point is B-picture, thereby enabling insertionediting on the frame basis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the recording format on a magnetic tape.

FIG. 2 illustrates the picture type of a coded stream.

FIG. 3 is a plan view showing arrangement of a magnetic head.

FIG. 4 shows scanning by the magnetic head on a magnetic tape.

FIG. 5 is a block diagram showing the overall structure of a video taperecorder.

FIGS. 6A to 6H are time charts for explaining delay of video data or acoded stream due to insertion editing.

FIGS. 7A to 7G illustrate processing at IN-point of insertion editing.

FIGS. 8A to 8G illustrate processing at OUT-point of insertion editing.

FIGS. 9A to 9H are time charts for explaining delay of video data or acoded stream due to another insertion editing.

FIGS. 10A to 10G illustrate processing at IN-point of another insertionediting.

FIGS. 11A to 11G illustrate processing at OUT-point of another insertionediting.

FIGS. 12A to 12E illustrate editing processing at IN-point of a typicalcoded stream.

FIGS. 13A to 13E illustrate editing processing at OUT-point of a typicalcoded stream.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be described indetail with reference to the drawings.

FIG. 1 is a plan view showing the recording format of a magnetic tape 1employed in a video tape recorder according to an embodiment of thepresent invention.

On the magnetic tape 1 of FIG. 1 employed in the video tape recorder,recording tracks AUX, CTL and TC for recording various signals areformed on upper and lower ends and in the longitudinal direction of themagnetic tape 1. Between these recording tracks AUX and CTL, obliquetracks are formed by sequential azimuth recording.

On the recording track AUX on the upper end of the longitudinalrecording tracks, auxiliary data such as analog audio signals and a cuesignal are recorded. On the recording track TC of the lower-endrecording tracks, a time code is recorded. The recording track CTL isallocated as a track for recording a timing signal for controlling arecording/reproduction system, and a control signal CTL having theone-cycle signal level switched by five tracks of the oblique tracks isrecorded.

The oblique tracks are formed in such a manner that each 10 recordingtracks (in the case of the NTSC signals) having a gap of two tracksbetween them are used as a unit. On these 10 recording tracks, a codedstream in accordance with the MPEG standard, audio data and system dataare recorded in predetermined arrangement.

Of the oblique tracks, areas on the scanning start side and the scanningend side of the magnetic head are allocated as video areas ARV, in whicha coded stream is recorded together with an error correction code inpredetermined arrangement. On the inner side of these video areas ARV,system data areas ARS are provided, each having a predetermined gap fromthe video area. These system data areas ARS are provided on the eightrecording tracks except for the leading track and the last track of the10 recording tracks. In these system data areas ARS, predeterminedsystem data and an error correction code are recorded.

As the system data, there are provided identification data indicatingthe order of the corresponding GOP and GOP preceding and subsequent tothe corresponding GOP, hysteresis data on which increment is made byinsertion editing and assemble editing, and edit point data indicatingedit points such as IN-point and OUT-point.

The identification data indicating the order of GOP includes sequentialnumbers appended to the individual GOP. In the present embodiment,numbers “0” to “7” are repeatedly appended to the respective GOP.

On the eight tracks having the system data areas ARS in each GOP, thesame identification data is recorded. For example, if the identificationdata of the corresponding GOP is “3”, the identification data of thepreceding GOP is “2” and the identification data of the subsequent GOPis “4”. Therefore, the identification data indicating “2”, “3” and “4”are recorded in the system data areas ARS in the corresponding GOP.

The reason for describing not only the identification data of thecorresponding GOP but also the identification data of the preceding andsubsequent GOP is that high-speed reproduction processing is to berealized by reading in advance the identification data of the precedingand subsequent GOP recorded as the system data, at the time of fast feetreproduction or rewind reproduction.

The hysteresis data is data on which increment is made by editingprocessing such as insertion editing and assemble editing, and isprovided for each track. If data recorded on the tape is original data,the hysteresis data of all the tracks are “0”. The hysteresis data of atrack which is newly overwritten by editing processing such as insertionediting is “1”. Every time such editing processing is repeated,increment is made on this hysteresis data.

On the inner side of the system data areas ARS, an audio data area ARAhaving a predetermined gap from the system data areas is provided. Thisaudio data area ARA is divided into eight sectors with a predeterminedgap provided between them, and audio data of four channels are allocatedand recorded in these sectors.

FIG. 2 illustrates compression coding processing of video data which isthus recorded on the magnetic tape 1. In this embodiment, codingprocessing is carried out on each picture so that continuous two frames(two pictures) constitute one GOP. The picture type of the leading frameof each GOP is B-picture obtained by inter-frame coding processing inwhich past and future frames are set as predictive frames. The picturetype of the subsequent frame is I-picture obtained by intra-frame codingprocessing.

In FIG. 2, the direction of prediction of B-picture is indicated byarrows. Each B-picture is predictive-coded from both the past I-pictureand the future I-picture.

FIG. 3 is a plan view showing arrangement of a magnetic head of thevideo tape recorder corresponding to the above-described recordingformat. In the video tape recorder of this embodiment, a recording headRECA and a recording head RECB are provided at a predetermined spacing(12.8 degrees) from each other on a rotary drum 3, and monitor heads PBAand PBB are provided at positions of 180 degrees from the recordingheads RECA and RECB, respectively.

As shown in FIG. 4, the recording heads RECA and RECB are provided atsuch positions that when the magnetic head scans the magnetic tape, therecording heads RECA and RECB are shifted by a half-track pitch to theforward side from the monitor heads PBA and PBB, on the magnetic tape.In short, the monitor heads PBA and PBB are caused to scan the scanninglocus of the corresponding recording heads RECA and RECB immediatelyafter the scanning by the recording heads RECA and RECB. Thus, in thevideo tape recorder, recording results can be monitored while recordingprocessing is carried out. On the rotary drum 3, the magnetic tape 1 iswound substantially at a winding angle of 180 degrees.

In addition, an erase head ER is provided at a position spaced away fromthe recording head RECA by 12.8 degrees on the rotary drum 3, as shownin FIG. 3. The erase head ER is provided at a position preceding therecording heads RECA and RECB so as to collectively scan the tworecording tracks to be scanned by the recording heads RECA and RECBimmediately before the scanning by the recording heads RECA and RECB, asshown in FIG. 4. By providing the erase head at such a positionpreceding the recording heads, overwrite recording can be carried out.

Also, on the rotary drum 3, advanced reading heads ADA1 and ADB1 areprovided at positions spaced away from the recording heads RECA and RECBby 102.8 degrees in the reverse rotating direction of the rotary drum 3.Moreover, advanced reading heads ADA2 and ADB2 are provided at positionsof 180 degrees from the advanced reading heads ADA1 and ADB1,respectively.

These advanced reading heads ADA1, ADB1 and advanced reading heads ADA2,ADB2 are provided on the rotary drum 3 so that the magnetic heads of thecorresponding azimuth angle have the same height. In the presentembodiment, even when recording tracks corresponding to the one pair ofadvanced reading heads (ADA1, ADB1) are scanned by off-tracking of onetrack, the other pair of advanced reading heads (ADA2, ADB2) can scanthe corresponding recording tracks by just tracking. Therefore, ultimatereproduced data can be provided by synthesizing the reproduced signalsfrom both the advanced reading heads ADA1, ADB1 and the advanced readingheads ADA2, ADB2.

Moreover, these advanced reading heads ADA1, ADB1 and advanced readingheads ADA2, ADB2 are positioned on the rotary drum so that the advancedreading heads ADA1, ADB1 on the following side are advanced by a66-track pitch (66Tp) from the recording heads RECA, RECB to scan themagnetic tape 1.

In the video tape recorder of the present embodiment, the total time ofthe delay time in reproduction processing required for decodingreproduced video data obtained by the advanced reading heads ADA1, ADB1on the preceding side and the delay time in recording processingrequired for compression-coding the video data and recording the codedvideo data onto the magnetic tape 1 is the time for 6.6 GOP. In thefollowing description, the time for 6.6 GOP found by totaling thereproduction processing time and the recording processing time isreferred to as a system delay.

As shown in FIG. 4, the track pitch 66Tp consisting of 66 tracks forrecording data of 6.6 GOP is equivalent to this system delay. That is,the positions of the advanced reading heads ADA1, ADB1, ADA2, ADB2 withrespect to the recording heads RECA, RECB are determined so as tocorrespond to the system delay.

Thus, in this video tape recorder, when the video data reproduced by theadvanced reading heads ADA1, ADB1 or the advanced reading heads ADA2,ADB2 are delayed by the system delay consisting of the reproductionprocessing time and the recording processing time, the recording headsRECA, RECB are about to scan the track on which the reproduced videodata have been originally recorded. Therefore, the video data reproducedby the advanced reading heads ADA1, ADB1 or the advanced reading headsADA2, ADB2 can be recorded at perfectly the same position as theoriginal position by the recording heads RECA, RECB. That is, insertionediting for inserting new video data at a desired edit point can berealized while the original video data are reproduced from the tape.

FIG. 5 is a block diagram showing the overall structure of a video taperecorder 10 of the embodiment of the present invention.

In this video tape recorder 10, a timing generator (TG) 11 receives anintra-station synchronizing signal REF, a source video signal, and aserial digital video signal (SDI). The timing generator 11 generates areference signal indicating the timing of each frame synchronized withthe intra-station synchronizing signal REF, source video signal orserial digital video signal, and supplies the reference signal to asystem controller 13.

A servo circuit 12 is a circuit for driving magnetic tape travelingsystem circuits such as a reel driving circuit and a capstan drivingcircuit provided in the video tape recorder 10, and a drum controlcircuit for controlling the rotational speed of the rotary drum, underthe control of the system controller 13. This servo circuit 12 forms 10recording tracks during a period of two frames (one GOP) as describedwith reference to FIG. 1, by controlling the tape traveling systemcircuits and the drum control circuit.

An I/O processing circuit 14 is a circuit for carrying out input signalprocessing of video signals and audio signals supplied from outside, andoutput signal processing of video signals and audio signals to beoutputted from the video tape recorder. For example, if the I/Oprocessing circuit 14 receives analog composite source video signalsfrom outside, it carries out analog-digital conversion processing of thevideo signals with reference to the reference signal generated by thetiming generator at the timing synchronized with the source videosignals, and then outputs the generated digital video signals as baseband video data consisting of continuous luminance data andcolor-difference data at a predetermined sampling rate. Also, the I/Oprocessing circuit 14 receives audio signals of four channelscorresponding to the source video signals and carries out signalprocessing of the audio signals similar to that of the source videosignals, thereby outputting audio data of four channels corresponding tothe base band video data.

If the I/O processing circuit 14 receives digital video signalsconsisting of sequentially continuous video data and audio data ofserial data of a predetermined format, it converts the digital videosignals to video data consisting of continuous luminance data andcolor-difference data, and audio data, and outputs the resulting videodata and audio data.

Also, the I/O processing circuit 14 carries out signal processing sothat the video data and audio data reproduced from the magnetic tape 1or edited video data and audio data outputted from switching circuits 16and 15 become serial video signals of a predetermined format, andcarries out signal processing so that the video data and audio databecome analog composite video signals and audio signals of fourchannels.

The switching circuit 15 is a circuit for switching the base band videodata outputted from the I/O processing circuit 14 and base band videodata outputted from an MPEG decoder 29 at edit points such as IN-pointand OUT-point under the control of the system controller 13. That is,this switching circuit 15 is a circuit for switching the base band videodata. The switching circuit 15 outputs the video data generated byswitching at the edit points, as edited video data to a filter circuit17. The switching circuit 16 is a circuit for carrying out the sameoperation as the above-described switching circuit 15 under the controlof the system controller 13. The switching circuit 16 switches the audiodata outputted from the I/O processing circuit 14 and audio dataoutputted from an outer code decoder 28 at edit points such as IN-pointand OUT-point, thereby outputting edited audio data.

For example, in recording source video data and source audio datasupplied from outside onto the magnetic tape 1, the terminals of theswitching circuits 15 and 16 are fixed to connection to the respectiveupper terminals so as to supply the video data and audio data outputtedfrom the I/O processing circuit 14 to the filter circuit 17 and an ECCencoder 20, respectively, under the control of the system controller 13.

On the other hand, in carrying out insertion editing for insertinginsertion video data supplied from outside into the video data alreadyrecorded on the magnetic tape 1, the switching operation of theswitching circuits 15 and 16 is changed over at edit points such asIN-point and OUT-point. Specifically, during a period up to IN-point,the terminals of the switching circuits 15 and 16 are connected to therespective lower terminals so as to supply the video data outputted fromthe MPEG decoder 29 and the audio data outputted form the outer codedecoder 28 to the filter circuit 17 and the ECC encoder 20,respectively. During a period from IN-point to OUT-point, the terminalsof the switching circuits 15 and 16 are connected to the respectiveupper terminals so as to supply the insertion video data and insertionaudio data outputted from the I/O processing circuit 14 to the filtercircuit 17 and the ECC encoder 20, respectively. During a period afterOUT-point, the terminals of the switching circuits 15 and 16 are againconnected to the respective lower terminals so as to supply the videodata outputted from the MPEG decoder 29 and the audio data outputtedfrom the outer code decoder 28 to the filter circuit 17 and the ECCencoder 20, respectively. Processing related to this insertion editingwill be later described in detail.

The filter 17 is a band-limiting filter for receiving video dataoutputted from the switching circuit 15 and limiting noise of the videodata. By reducing noise in a high-frequency range of the video data bythis filter 17, the compression coding efficiency in an MPEG encoder 19on the subsequent stage can be improved.

The MPEG encoder 19 encodes the base band video data outputted from thefilter 17 in conformity to the MPEG2 standard, and outputs a codedstream. The MPEG encoder 19 carries out coding processing with twoframes as one GOP. The MPEG encoder 19 encodes the first picture asB-picture, which is bidirectionally predicted from past and futureI-picture, and encodes the next picture as I-picture, which is obtainedby intra-frame coding. Thus, the MPEG encoder 19 generates a codedstream consisting of BIBIBI . . . as shown in FIG. 2. In addition, theMPEG encoder 19 detects the quantity of bits generated in coding eachGOP, and controls the quantization step size and the quantization scalein accordance with the detection result so that the quantity ofgenerated bits for each GOP corresponds to 10 tracks. Thus, the MPEGencoder 19 can generate a coded stream having a fixed quantity of bitsfor each GOP.

The ECC encoder 20 receives the coded stream outputted from the MPEGencoder 19, then generates an error correction code (ECC) in the form ofproduct code based on one GOP as a unit with respect to the codedstream, and generates a coded stream having the error correction codeadded thereto. The ECC encoder 20 carries out processing for forming thecoded stream having the ECC added thereto based on the coded stream ofone GOP as a unit. In addition, the ECC encoder 20 receives the audiodata outputted from the switching circuit 16, then generates an errorcorrection code with respect to the audio data corresponding to thecoded video stream of one GOP, and generates audio data having the errorcorrection code added thereto. Similarly, the ECC encoder 20 receivessystem data from the system controller 13, then generates an errorcorrection code in the form of product code by each GOP of the codedvideo stream, and forms system data having the error correction codedadded thereto.

The error correction code to be added to the video coded stream and theaudio data is made of an outer code parity and inner code parity, andthe error correction code to be added to the system data is made only ofan inner code parity.

As described with reference to FIG. 1, the video tape recorder 10 inthis embodiment records the coded video stream having the errorcorrection code added thereto and the audio data having the errorcorrection code added thereto onto 10 recording tracks in a dispersedmanner. Therefore, the error correction code has such an errorcorrection capability that even when video data and audio data of twotracks cannot be reproduced from the magnetic tape, the video data ofthe two tracks that cannot be reproduced can be reproduced by using theerror correction codes of the video data and audio data reproduced fromthe remaining eight tracks. In short, in the ECC encoder 20, the codecapability and code length of the error correction code are set so thatthe original video data and audio data can be decoded to a practicallysufficient degree by carrying out error correction processing ofreproduced data obtained from at least eight recording tracks of the 10recording tracks.

Moreover, the ECC encoder 20 carries out shuffling processing byshuffling the arrangement of the coded video stream having the errorcorrection code added thereto and the audio data having the errorcorrection code added thereto, for each predetermined block unit. Inaddition, the ECC encoder 20 adds identification data ID to the shuffledpredetermined block and outputs the resulting block. The identificationdata ID is data to be added for reproducing the coded video streamhaving the error correction code added thereto and the audio data havingthe error correction code added thereto by de-shuffling the reproduceddata from the magnetic tape.

A recording circuit 23 generates recording data by carrying outmodulation and amplification of the coded video stream, audio data andsystem data outputted from the ECC encoder 20, under the control of thesystem controller 13, and supplies the generated recording data to therecording heads RECA, RECB in accordance with a recording timing controlsignal supplied from the system controller 13. Specifically, when therecording timing control signal is at a high level, the recording datagenerated by the recording circuit 23 is recorded onto the magnetic tape1 by overwriting through the recording heads RECA, RECB. When therecording timing control signal is at a low level, the recording datagenerated by the recording circuit 23 is not outputted from therecording circuit 23. Therefore, the recording data is not recorded ontothe magnetic tape 1. The recording timing control signal supplied fromthe system controller 13 will be later described in detail.

In the video tape recorder 10 of the present embodiment, a fixed delaytim for 8.47 frames is generated by a recording processing system whichis constituted by the filter 17, the MPEG encoder 19, the ECC encoder 20and the recording circuit 23.

Reproducing circuits 24 and 25 output reproduced data by amplifying andwave-shaping reproduced signals obtained from the monitor heads PBA, PBBand from the advanced reading heads ADA1 to ADB2, respectively.

In the video tape recorder of the present embodiment, while recordingoperation for recording data onto the magnetic tape by the recordingheads RECA and RECB is carried out, the data recorded on the magnetictape 1 by the recording heads RECA and RECB are immediately reproducedby the monitor heads PBA and PBB. Thus, the data recorded on themagnetic tape 1 can be monitored. A reproduced signal processing circuit26 outputs reproduced data by synthesizing the reproduced signals fromthe monitor heads PBA, PBB outputted from the reproducing circuit 24, atthe time of data recording. The reason for synthesizing reproducedsignals from the two monitor heads PBA, PBB to provide one reproduceddata is as follows. That is, if reproduced data is generated from thesignals reproduced from one monitor head, data of the recording trackcannot be accurately reproduced in the case where tracking of therecording track with respect to the monitor head is deviated.

At the time of data reproduction, the reproduced signal processingcircuit 26 generates reproduced data by synthesizing reproduced signalsof the advanced heads ADA1 and ADB1 outputted from the reproducingcircuit 25, and generates reproduced data by synthesizing reproducedsignals of the advanced reading heads ADA2 and ADB2. The reproduced dataoutputted from the reproduced signal processing circuit 26 is the sameas the data outputted from the ECC encoder 20.

An inner code decoder 27 receives the reproduced coded video stream,reproduced audio data and reproduced system data outputted from thereproduced signal processing circuit 26, and carries out errorcorrection processing of the reproduced coded video stream by using theinner code parity added to the reproduced video data as an errorcorrection code. The inner code decoder 27 then outputs theerror-corrected reproduced coded video stream together with the errorcorrection processing result. Also, the inner code decoder 27 carriesout error correction processing of the reproduced audio data by usingthe inner code parity added to the reproduced audio data as an errorcorrection code, and outputs the error-corrected reproduced audio datatogether with the error correction result. In addition, the inner codedecoder 27 carries out error correction processing of the reproducedsystem data by using the inner code parity added to the reproducedsystem data, and supplies the error-corrected reproduced system data tothe system controller 13.

The outer code decoder 28 is a circuit for receiving the coded videostream and audio data outputted from the inner code decoder 27 andcarrying out error correction processing of the coded video stream andaudio data on the basis of the outer code parity added to the respectivedata. Specifically, the outer code decoder 28 stores the coded videostream outputted from the inner code decoder 27 into a built-in memorythereof, and carries out error correction processing by using the outercode parity added to the coded video stream. The coded video stream onwhich error correction processing has been carried out by the outer codeparity is supplied to the MPEG decoder 29. Also, the outer code decoder28 stores the audio data outputted from the inner code decoder 27 intothe built-in memory, and carries out error correction processing byusing the outer code parity added to the audio data. The audio data onwhich error correction processing has been carried out by the outer codeparity is supplied to the I/O processing circuit and the switchingcircuit 16.

The MPEG decoder 29 receives the coded video stream outputted from theouter code decoder 28, then decodes the coded video stream in accordancewith the MPEG2 standard, and generates base band video data. The baseband video data decoded by the MPEG decoder 29 is supplied to the I/Oprocessing circuit 14 and the switching circuit 15.

In the video tape recorder 10 of the present embodiment, a fixed delaytime for 4.64 frames is generated in a reproduction processing systemwhich is constituted by the reproducing circuits 24, 25, the reproducedsignal processing circuit 26, the inner code decoder 27, the outer codedecoder 28 and the MPEG decoder 29.

In short, in the video tape recorder 10 of the present embodiment, asystem delay for 13.2 frames corresponding to 66 tracks is generated bycombining the delay times in the recording processing system and thereproduction processing system.

The control by the system controller 13 in carrying out insertionediting for newly inserting video data into the original video datarecorded on the magnetic tape will now be described in detail withreference to FIGS. 6A to 11G.

FIGS. 6A to 6H are time charts showing the timing of output data and arecording control signal in insertion editing processing. FIG. 6A showsa coded video stream ST_(ORG) reproduced from the magnetic tape by theadvanced reading heads ADA1 to ADB2. FIG. 6B shows original video dataV_(ORG) of the base band outputted from the MPEG decoder 29. FIG. 6Cshows insertion video data V_(INS) of the base band to be inserted intothe original video data V_(ORG). FIG. 6D shows edited video dataV_(EDIT) of the base band outputted from the switching circuit 15. FIG.6E shows an edited coded stream ST_(EDIT) outputted from the ECC encoder20. FIG. 6F shows a recording timing control signal RT_(V) forcontrolling the recording timing of the edited coded video stream. FIG.6G shows a recording timing control signal RT_(S) for controlling therecording timing of the system data. FIG. 6H shows a recording timingcontrol signal RT_(A) for controlling the recording timing of the audiodata.

In the following description, a coded stream which is already recordedon the magnetic tape before carrying out insertion editing processing isreferred to as an original coded stream.

In the example shown in FIG. 6A, IN-point is set between a picture B2and a picture I3 in the original coded stream ST_(ORG), and OUT-point isset between a picture B8 and a picture I9. In this example, insertionvideo data V_(INS) supplied from an external unit is inserted betweenthe picture I3 and the picture B8 of the original video data V_(ORG)obtained by MPEG-decoding the original coded stream ST_(ORG) reproducedfrom the magnetic tape.

As described already, in the video tape recorder of the presentembodiment, since the delay time for 4.64 frames is generated in thereproduction processing system which is constituted by the reproducingcircuits 24, 25, the reproduced signal processing circuit 26, the innercode decoder 27, the outer code decoder 28 and the MPEG decoder 29, thebase band video data V_(ORG) outputted from the MPEG decoder 29 isdelayed by 4.64 frames with respect to the original coded streamST_(ORG) reproduced from the magnetic tape.

In the base band video data V_(ORG) outputted from the MPEG decoder 29,IN-point is set between the picture B2 and the picture I3 and OUT-pointis set between the picture B8 and the picture I9, as shown in FIG. 6B.When insertion editing is carried out for inserting video data from apicture I3′ to a picture B8′ of the insertion video data into a sectiondesignated by the IN-point and OUT-point as shown in FIG. 6C, the editedvideo data V_(EDIT) as shown in FIG. 6D is generated.

Practically, this insertion editing is carried out as the systemcontroller 13 controls the switching operation of the switching circuits15 and 16 at the timing of IN-point and OUT-point. Specifically, duringthe period up to IN-point, the terminal of the switching circuit 15 isconnected to the lower terminal, and the base band video data V_(ORG)reproduced from the magnetic tape is outputted as the edited video dataV_(EDIT) from the switching circuit 15. During the period from IN-pointto OUT-point, the terminal of the switching circuit 15 is connected tothe upper terminal, and the insertion video data VN_(INS) is outputtedas the edited video data V_(EDIT) from the switching circuit 15. Duringthe period after OUT-point, the terminal of the switching circuit 15 isconnected again to the lower terminal, and the base band video dataV_(ORG) reproduced from the magnetic tape is outputted again as theedited video data V_(EDIT) from the switching circuit 15. As a result ofsuch switching operation of the switching circuit 15, the edited videodata V_(EDIT) as shown in FIG. 6D is generated.

The edited video data V_(EDIT) is supplied to the MPEG encoder 19through the filter circuit 17. The MPEG encoder 19 encodes the editedvideo data V_(EDIT) in conformity to the MPEG2 standard and outputs theresultant data as the edited coded stream ST_(EDIT), as describedalready. The ECC encoder 20 adds an error correction code to the editedcoded stream ST_(EDIT) and outputs the resultant coded stream as theedited coded stream ST_(EDIT) having the error correction code addedthereto, as shown in FIG. 6E.

Since the fixed delay for 8.4 frames is generated in the recordingprocessing system which is constituted by the filter 17, the MPEGencoder 19 and the ECC encoder 20, the edited coded stream ST_(EDIT)outputted from the ECC encoder 20 is delayed by 8.4 frames with respectto the edited video data V_(EDIT) outputted from the switching circuit15, as relatively shown in FIGS. 6D and 6E. In short, the edited codedstream ST_(EDIT) to be recorded onto the magnetic tape is delayed by 6.6GOP with respect to the original coded video stream ST_(ORG) reproducedfrom the magnetic tape.

In the video tape recorder 10 of the present embodiment, the advancedreading heads ADA1 and ADB1 are advanced by 6.6 GOP with respect to therecording heads RECA and RECB, as described in FIG. 4. Therefore, whenthe data stream reproduced from the advanced heads ADA1 and ADB1 issupplied to the recording heads RECA and RECB through the reproductionprocessing system and the recording processing system, the magnetic headdrum is rotated for a predetermined number of times and the magnetictape is moved on the magnetic head by a predetermined amount, duringthat period. Thus, the data stream can be recorded at perfectly the sameposition on the magnetic tape by the recording heads RECA and RECB.

In the example shown in FIGS. 6A to 6H, when the original picture B2 isreproduced from the magnetic tape by the advanced reading heads ADA1 andADB1 and then a new picture B2 obtained by decoding processing in thereproduction processing system and encoding processing in the recordingprocessing system is recorded onto the magnetic tape by the recordingheads RECA and RECB, the recording position on the magnetic tape wherethe original picture B2 was recorded and the recording position of thenewly obtained picture B2 are perfectly the same.

That is, in the example of FIGS. 6A to 6H, the recording position on themagnetic tape of the picture I3 of the original coded stream and therecording position on the magnetic tape of the picture I3′ of the editedcoded stream are perfectly the same. Thus, insertion editing processingis carried out by recording the pictures I3′, B4′, I5′, B6′, I7′ and B8′of the edited coded stream at the same positions as those of thepictures I3, B4, I5, B6, I7 and B8 of the original coded stream byoverwriting.

With reference to FIGS. 7A to 7G, the timing for recording the codedvideo stream, the timing for recording the system data and the timingfor recording the audio data in the case where this insertion editing iscarried out will now be described. FIG. 7A shows original data V_(ORG)of the base band outputted from the MPEG decoder 29. FIG. 7B showsinsertion video data V_(INS) of the base band to be inserted into theoriginal video data V_(ORG). FIG. 7C shows edited video data V_(EDIT) ofthe base band outputted from the switching circuit 15. FIG. 7D shows anedited coded stream ST_(EDIT) outputted from the ECC encoder 20. FIG. 7Eshows a recording timing control signal RT_(V) for controlling therecording timing of the edited coded video stream. FIG. 7F shows arecording timing control signal RT_(S) for controlling the recordingtiming of the system data. FIG. 7G shows a recording timing controlsignal RT_(A) for controlling the recording timing of the audio data.

Since FIGS. 7A to 7G are views for explaining the recording timingcontrol signal RT_(V) at IN-point, the timing of OUT-point is notdescribed.

In carrying out insertion editing, the system controller 13 controls therecording circuit 23 to record the edited coded stream ST_(EDIT) ontothe magnetic tape in accordance with the recording timing control signalRT_(V) shown in FIG. 7E, instead of recording all the edited codedstreams ST_(EDIT) outputted from the ECC encoder 20 onto the magnetictape.

In this case, the pictures from IN-point (i.e., pictures from thepicture I3′) of the insertion video data VN_(INS) are recorded onto themagnetic tape by overwriting, but a picture B0 and a picture I1 of theedited coded stream ST_(EDIT) are not recorded onto the magnetic tape.This is because a picture B0 and a picture I1 of the original codedstream ST_(ORG) are already recorded on the magnetic tape. Since thepicture B0 and picture I1 of the edited coded stream ST_(EDIT) which isre-encoded are processed by MPEG decoding processing and MPEGre-encoding processing, the picture quality of these pictures isslightly deteriorated from that of the picture B0 and picture I1 of theoriginal coded stream ST_(ORG). Therefore, it is not necessary to recordthe picture B0 and picture I1 of the slightly deteriorated picturequality by overwriting the picture B0 and picture I1 of the originalcoded stream ST_(ORG) of the good picture quality.

In the video tape recorder of the present embodiment, on the basis ofthe recording timing control signal RT_(V) shown in FIG. 7E, the pictureB2 of the edited coded stream ST_(EDIT) is recorded to overwrite thepicture B2 of the original coded stream ST_(ORG) recorded on themagnetic tape. This is because the picture B2 of the edited coded streamST_(EDIT) is different from the picture B2 of the original coded streamST_(ORG) already recorded on the magnetic tape. The reason why thepicture B2 of the edited coded stream ST_(EDIT) is different from thepicture B2 of the original coded stream ST_(ORG) already recorded on themagnetic tape will be described hereinafter.

The picture B2 of the original coded stream ST_(ORG) recorded on themagnetic tape is a picture predictively coded from both the futurepicture I1 and the past picture I3, and the picture B2 of the editedcoded stream ST_(EDIT) generated by insertion editing processing is apicture predictively coded from both the future picture I1 and the pastpicture I3′. That is, since these pictures are based on differentprediction target pictures, the DCT coefficient and coding parameter ofthe picture B2 of the edited coded stream ST_(EDIT) are different fromthe DCT coefficient and coding parameter of the picture B2 of theoriginal coded stream ST_(ORG) already recorded on the magnetic tape.

Also, in the video tape recorder of the embodiment of the presentinvention, coding processing is carried out so that a coded stream forone GOP corresponds to the data quantity for 10 tracks, as describedabove. In short, the original coded stream ST_(ORG) is a stream which iscoded so that the data quantity obtained by combining the data quantityof the picture B2 and the data quantity of the picture I3 in this streamcorresponds to the data quantity for 10 tracks. The edited coded streamST_(EDIT) generated by insertion editing is a stream which is re-encodedso that the data quantity obtained by combining the quantity ofgenerated data of the picture B2 and the quantity of generated data ofthe picture I3′ in this stream corresponds to the data quantity for 10tracks. As a result, the data quantity of the picture B2 of the originalcoded stream ST_(ORG) and the data quantity of the picture B2 of theedited coded stream are totally different from each other.

The system controller 13 controls the recording circuit 23 to rewritethe picture B2 of the original coded stream ST_(ORG) recorded on themagnetic tape by the picture B2 of the edited coded stream ST_(EDIT)which is encoded by insertion editing. In short, the system controller13 generates the recording timing control signal RT_(V) for rewritingthe picture B2 and supplies this recording timing control signal RT_(V)to the recording circuit 23, thereby rewriting the picture. B2 of theoriginal coded stream ST_(ORG) recorded on the magnetic tape by thepicture B2 of the edited coded stream ST_(EDIT) which is encoded byinsertion editing.

When the recording timing control signal RT_(V) supplied from the systemcontroller 13 is at a low level, the recording circuit 23 does not carryout processing for recording the edited coded stream ST_(EDIT) suppliedfrom the ECC encoder 20 onto the magnetic tape. When the recordingtiming control signal RT_(V) supplied from the system controller 13 isat a high level, the recording circuit 23 carries out processing forrecording the edited coded stream ST_(EDIT) supplied from the ECCencoder 20 onto the magnetic tape by overwriting.

Moreover, the system controller 13 controls the recording circuit 23 torecord the system data supplied from the ECC encoder 20 on the basis ofthe recording timing control signal RT_(S) with respect to the systemdata shown in FIG. 7F. That is, processing for recording the system databy overwriting advanced by one GOP from the recording timing of thecoded stream is carried out, instead of starting recording of the systemdata at the same timing as that of the coded video stream described inFIG. 7E. In the video tape recorder of the present embodiment, to carryout variable-speed reproduction, identification ID of the preceding GOPand identification ID of the subsequent GOP are recorded as the systemdata.

Since GOP1 consisting of the picture B2 and picture I3′ is rewritten bythis insertion editing, identification ID of GOP1 is changed. Thus, tochange the identification ID of GOP1 described in the system data ofGOP0, overwrite processing for recording the system data is carried outat the timing advanced by one GOP from the recording timing of the codedstream.

In addition, the system controller 13 controls the recording circuit 23to record the audio data supplied from the ECC encoder 20 on the basisof the recording timing control signal RT_(A) with respect to the audiodata shown in FIG. 7G. Since the audio data is not compression-coded,the system delay in the reproduction processing system and the recordingprocessing system is smaller than that of the video data. Therefore, therecording timing of the audio data at IN-point may be equal to therecording timing of the coded video stream.

With reference to FIGS. 8A to 8G, the timing for recording the codedvideo stream, the timing for recording the system data and the timingfor recording the audio data at OUT-point in this insertion editing willnow be described. FIG. 8A shows original data V_(ORG) of the base bandoutputted from the MPEG decoder 29. FIG. 8B shows insertion video dataV_(INS) of the base band to be inserted into the original video dataV_(ORG). FIG. 8C shows edited video data V_(EDIT) of the base bandoutputted from the switching circuit 15. FIG. 8D shows an edited codedstream ST_(EDIT) outputted from the ECC encoder 20. FIG. 8E shows arecording timing control signal RT_(V) for controlling the recordingtiming of the edited coded video stream. FIG. 8F shows a recordingtiming control signal RT_(S) for controlling the recording timing of thesystem data. FIG. 8G shows a recording timing control signal RT_(A) forcontrolling the recording timing of the audio data.

Since FIGS. 8A to 8G are views for explaining the recording timingcontrol signal at OUT-point, the timing of IN-point is not described.

The system controller 13 controls the recording circuit 23 to record theedited coded stream ST_(EDIT) outputted from the ECC encoder 20 onto themagnetic tape on the basis of the recording timing control signalRT_(V). As described with reference to FIGS. 7A to 7G, the systemcontroller 13 does not record all the edited coded streams ST_(EDIT)outputted from the ECC encoder 20 onto the magnetic tape. Actually, thepictures up to OUT-point (i.e., pictures up to the picture B6′) of theinsertion video data are recorded onto the magnetic tape by overwriting,but a picture B10 and a picture I11 of the edited coded stream ST_(EDIT)are not recorded onto the magnetic tape. This is because a picture B10and a picture I11 of the original coded stream ST_(ORG) are alreadyrecorded on the magnetic tape. Since the picture B10 and picture I11 ofthe edited coded stream ST_(EDIT) are processed by MPEG decodingprocessing and MPEG re-encoding processing, the picture quality of thesepictures is slightly deteriorated from that of the picture B10 andpicture I11 of the original coded stream ST_(ORG). Therefore, it is notnecessary to record the picture B10 and picture I11 of the slightlydeteriorated picture quality by overwriting the picture B10 and pictureI11 of the original coded stream ST_(ORG) of the good picture quality.

However, pictures I7, B8 and I9 of the edited coded stream ST_(EDIT)outputted from the ECC encoder 20 are recorded onto the magnetic tape byoverwriting on the basis of the recording timing control signal RT_(V).This is because the DCT coefficients, coding parameters and quantitiesof generated data of the pictures I7, B8 and I9 of the edited codedstream ST_(EDIT) generated by insertion editing are totally differentfrom those of the pictures I7, B8 and I9 of the original coded streamST_(ORG) already recorded on the magnetic tape.

In the video tape recorder of the embodiment of the present invention,the MPEG encoder 19 encodes the picture B6′ and the picture I7 so thatthe data quantity obtained by combining the quantity of generated bitsof the picture B6′ and the quantity of generated bits of the picture I7of the edited coded stream ST_(EDIT) obtained by insertion editingprocessing corresponds to the data quantity for 10 tracks. In short, thedata quantity obtained by combining the quantity of generated data ofthe picture B6 and the quantity of generated data of the picture I7 inthe original coded stream ST_(ORG) corresponds to the data quantity for10 tracks. The data quantity obtained by combining the quantity ofgenerated data of the picture B6′ and the quantity of generated data ofthe picture I7 in the edited coded stream ST_(EDIT) corresponds to thedata quantity for 10 tracks. Thus, the quantity of generated data of thepicture I7 of the edited coded stream ST_(EDIT) generated by re-encodingprocessing by the MPEG encoder 19 in insertion editing and the quantityof generated data of the picture I7 of the original coded streamST_(ORG) recorded on the magnetic tape are totally different from eachother.

The picture B8 of the original coded stream ST_(ORG) is a picturepredictively coded bidirectionally from the picture I7 of the originalcoded stream ST_(ORG) and the picture I9 of the original coded streamST_(ORG). However, as described above, the picture B8 of the editedcoded stream ST_(EDIT) is a picture predictively coded from the pictureI7 re-encoded by the MPEG encoder 19 and the picture I9 re-encoded bythe MPEG encoder 19. Therefore, the prediction target picture of thepicture B8 of the original coded stream ST_(ORG) and the predictiontarget picture of the picture B8 of the edited coded stream ST_(EDIT)are different from each other.

The data quantity obtained by combining the quantity of generated dataof the picture B8 and the quantity of generated data of the picture I9of the original coded stream ST_(ORG) corresponds to the data quantityfor 10 tracks, and the data quantity obtained by combining the quantityof generated data of the picture B8 and the quantity of generated dataof the picture I9 of the edited coded stream ST_(EDIT) corresponds tothe data quantity for 10 tracks. Therefore, the quantity of generateddata of the picture I9 of the edited coded stream ST_(EDIT) generated byre-encoding by the MPEG encoder 19 in insertion editing is differentfrom the quantity of generated data of the picture I9 of the originalcoded stream ST_(ORG) recorded on the magnetic tape.

As described above, the pictures I7, B8 and 19 of the edited codedstream ST_(EDIT) generated by insertion editing are different from thepictures I7, B8 and I9 of the original coded stream ST_(ORG) recorded onthe magnetic tape in terms of the quantity of generated data, theprediction target picture and the coding parameter. Therefore, thesystem controller 13 controls the recording circuit 23 to rewrite thepictures I7, B8 and I9 of the original coded stream ST_(ORG) recorded onthe magnetic tape by the pictures I7, B8 and I9 of the edited codedstream ST_(EDIT) generated by insertion editing, on the basis of therecording timing control signal RT_(V).

Moreover, the system controller 13 controls the recording circuit 23 torecord the system data supplied from the ECC encoder 20 on the basis ofthe recording timing control signal RT_(S) with respect to the systemdata shown in FIG. 8F. That is, processing for endingoverwrite-recording of the system data delayed by one GOP from therecording timing of the coded stream is carried out, instead of endingrecording of the system data at the same timing as that of the codedvideo stream described in FIG. 8E. In the video tape recorder of thepresent embodiment, to carry out variable-speed reproduction,identification ID of the preceding GOP and identification ID of thesubsequent GOP are recorded as the system data. That is, since GOP4consisting of the picture B8 and picture I9 of the edited coded streamST_(EDIT) is rewritten by this insertion editing, the system datacorresponding to GOP5 is rewritten so as to change identification ID ofGOP4 to be recorded as the system data of GOP5.

In addition, the system controller 13 controls the recording circuit 23to record the audio data supplied from the ECC encoder 20 on the basisof the recording timing control signal RT_(A) with respect to the audiodata shown in FIG. 8G. Since the audio data is not compression-coded,the system delay in the reproduction processing system and the recordingprocessing system is smaller than that of the video data. Therefore, therecording timing of the audio data at OUT-point may be equal to therecording timing of the coded video stream.

FIGS. 9A to 9H are time charts showing the timing of output data and arecording control signal in another insertion editing processing whichis different from insertion editing processing described in FIGS. 6A to6H. FIG. 9A shows a coded video stream ST_(ORG) reproduced from themagnetic tape by the advanced reading heads ADA1 to ADB2. FIG. 9B showsoriginal video data V_(ORG) of the base band outputted from the MPEGdecoder 29. FIG. 9C shows insertion video data V_(INS) of the base bandto be inserted into the original video data V_(ORG). FIG. 9D showsedited video data V_(EDIT) of the base band outputted from the switchingcircuit 15. FIG. 9E shows an edited coded stream ST_(EDIT) outputtedfrom the ECC encoder 20. FIG. 9F shows a recording timing control signalRT_(V) for controlling the recording timing of the edited coded videostream. FIG. 9G shows a recording timing control signal RT_(S) forcontrolling the recording timing of the system data. FIG. 9H shows arecording timing control signal RT_(A) for controlling the recordingtiming of the audio data.

In the example shown in FIG. 9A, IN-point is set between a picture I1and a picture B2 in the original coded stream ST_(ORG), and OUT-point isset between a picture 17 and a picture B8. In this example, insertionvideo data V_(INS) supplied from an external unit is inserted betweenthe picture B2 and the picture I7 of the original video data V_(ORG)obtained by MPEG-decoding the original coded stream ST_(ORG) reproducedfrom the magnetic tape.

As described already, in the video tape recorder of the presentembodiment, since the delay time for 4.64 frames is generated in thereproduction processing system which is constituted by the reproducingcircuits 24, 25, the reproduced signal processing circuit 26, the innercode decoder 27, the outer code decoder 28 and the MPEG decoder 29, thebase band video data V_(ORG) outputted from the MPEG decoder 29 isdelayed by 4.64 frames with respect to the original coded streamST_(ORG) reproduced from the magnetic tape.

In the base band video data V_(ORG) outputted from the MPEG decoder 29,IN-point is set between the picture I1 and the picture B2 and OUT-pointis set between the picture I7 and the picture B8, as shown in FIG. 9B.When insertion editing is carried out for inserting video data from apicture B2′ to a picture I7′ of the insertion video data into a sectiondesignated by the IN-point and OUT-point as shown in FIG. 9C, the editedvideo data V_(EDIT) as shown in FIG. 9D is generated.

Practically, this insertion editing is carried out as the systemcontroller 13 controls the switching operation of the switching circuits15 and 16 at the timing of IN-point and OUT-point. Specifically, duringthe period up to IN-point, the terminal of the switching circuit 15 isconnected to the lower terminal, and the base band video data V_(ORG)reproduced from the magnetic tape is outputted as the edited video dataV_(EDIT) from the switching circuit 15. During the period from IN-pointto OUT-point, the terminal of the switching circuit 15 is connected tothe upper terminal, and the insertion video data V_(INS) is outputted asthe edited video data V_(EDIT) from the switching circuit 15. During theperiod after OUT-point, the terminal of the switching circuit 15 isconnected again to the lower terminal, and the base band video dataV_(ORG) reproduced from the magnetic tape is outputted again as theedited video data V_(EDIT) from the switching circuit 15. As a result ofsuch switching operation of the switching circuit 15, the edited videodata V_(EDIT) as shown in FIG. 9D is generated.

The edited video data V_(EDIT) is supplied to the MPEG encoder 19through the filter circuit 17. The MPEG encoder 19 encodes the editedvideo data V_(EDIT) in conformity to the MPEG2 standard and outputs thecoded MPEG stream as the edited coded stream ST_(EDIT), as describedalready. The ECC encoder 20 adds an error correction code to the editedcoded stream ST_(EDIT) and outputs the resultant coded stream as theedited coded stream ST_(EDIT) having the error correction code addedthereto, as shown in FIG. 9E.

Since the fixed delay for 8.4 frames is generated in the recordingprocessing system which is constituted by the filter 17, the MPEGencoder 19 and the ECC encoder 20, the edited coded stream ST_(EDIT)outputted from the ECC encoder 20 is delayed by 8.4 frames with respectto the edited video data V_(EDIT) outputted from the switching circuit15, as relatively shown in FIGS. 9D and 9E. In short, the edited codedstream ST_(EDIT) to be recorded onto the magnetic tape is delayed by 6.6GOP with respect to the original coded video stream ST_(ORG) reproducedfrom the magnetic tape.

In the video tape recorder 10 of the present embodiment, the advancedreading heads ADA1 and ADB1 are advanced by 6.6 GOP with respect to therecording heads RECA and RECB, as described in FIG. 4. Therefore, whenthe data stream reproduced from the advanced heads ADA1 and ADB1 issupplied to the recording heads RECA and RECB through the reproductionprocessing system and the recording processing system, the magnetic headdrum is rotated for a predetermined number of times and the magnetictape is moved on the magnetic head by a predetermined amount, duringthat period. Thus, the data stream can be recorded at perfectly the sameposition on the magnetic tape by the recording heads RECA and RECB.

In the example shown in FIGS. 9A to 9H, on the assumption that theoriginal picture B0 is reproduced from the magnetic tape by the advancedreading heads ADA1 and ADB1 and then a new picture B0 obtained bydecoding processing in the reproduction processing system and encodingprocessing in the recording processing system is recorded onto themagnetic tape by the recording heads RECA and RECB, the recordingposition on the magnetic tape where the original picture B0 was recordedand the recording position of the newly obtained picture B0 areperfectly the same.

That is, in the example of FIGS. 9A to 9H, the recording position on themagnetic tape of the picture B2 of the original coded stream and therecording position on the magnetic tape of the picture B2′ of the editedcoded stream are perfectly the same. Thus, insertion editing processingis carried out by recording the pictures B2′, I3′, B4′, I5′, B6′ and I7′of the edited coded stream at the same positions as those of thepictures B2, I3, B4, I5, B6 and I7 of the original coded stream byoverwriting.

With reference to FIGS. 10A to 10G, the timing for recording the codedvideo stream, the timing for recording the system data and the timingfor recording the audio data in the case where this insertion editing iscarried out will now be described. FIG. 10A shows original data V_(ORG)of the base band outputted from the MPEG decoder 29. FIG. 10B showsinsertion video data V_(INS) of the base band to be inserted into theoriginal video data V_(ORG). FIG. 10C shows edited video data V_(EDIT)of the base band outputted from the switching circuit 15. FIG. 10D showsan edited coded stream ST_(EDIT) outputted from the ECC encoder 20. FIG.10E shows a recording timing control signal RT_(V) for controlling therecording timing of the edited coded video stream. FIG. 10F shows arecording timing control signal RT_(S) for controlling the recordingtiming of the system data. FIG. 10G shows a recording timing controlsignal RT_(A) for controlling the recording timing of the audio data.

Since FIGS. 10A to 10G are views for explaining the recording timingcontrol signal RT_(V) at IN-point, the timing of OUT-point is notdescribed.

In carrying out insertion editing, the system controller 13 controls therecording circuit 23 to record the edited coded stream ST_(EDIT) ontothe magnetic tape in accordance with the recording timing control signalRT_(V) shown in FIG. 10E, instead of recording all the edited codedstreams ST_(EDIT) outputted from the ECC encoder 20 onto the magnetictape.

In this case, the pictures from IN-point (i.e., pictures from thepicture B2′) of the insertion video data V_(INS) are recorded onto themagnetic tape by overwriting, but a picture B0 and a picture I1 of theedited coded stream ST_(EDIT) are not recorded onto the magnetic tape.This is because a picture B0 and a picture I1 of the original codedstream ST_(ORG) are already recorded on the magnetic tape. Since thepicture B0 and picture I1 of the edited coded stream ST_(EDIT) which isre-encoded are processed by MPEG decoding processing and MPEGre-encoding processing, the picture quality of these pictures isslightly deteriorated from that of the picture B0 and picture I1 of theoriginal coded stream ST_(ORG). Therefore, it is not necessary to recordthe picture B0 and picture I1 of the slightly deteriorated picturequality by overwriting the picture B0 and picture I1 of the originalcoded stream ST_(ORG) of the good picture quality.

Meanwhile, in the example shown in FIGS. 7A to 7G, the picture B2immediately before IN-point in the edited coded stream ST_(EDIT) isrecorded onto the magnetic tape by overwriting in accordance with therecording timing control signal RT_(V). This is because the picture B2immediately before IN-point in the edited coded stream ST_(EDIT)generated as a result of insertion editing processing is different fromthe picture B2 of the original coded stream ST_(ORG) recorded on themagnetic tape.

However, in the example shown in FIGS. 10A to 10G, the picture I1immediately before IN-point in the edited coded stream ST_(EDIT) is notrecorded onto the magnetic tape by overwriting. This is because thepicture I1 immediately before IN-point in the edited coded streamST_(EDIT) generated as a result of insertion editing processing is thesame as the picture I1 of the original coded stream ST_(ORG) recorded onthe magnetic tape. In other words, the picture I1 immediately beforeIN-point in the edited coded stream ST_(EDIT) generated as a result ofinsertion editing processing is a picture which is not affected byinsertion editing processing.

When the recording timing control signal RT_(V) supplied from the systemcontroller 13 is at a low level, the recording circuit 23 does not carryout processing for recording the edited coded stream ST_(EDIT) suppliedfrom the ECC encoder 20 onto the magnetic tape. When the recordingtiming control signal RT_(V) supplied from the system controller 13 isat a high level, the recording circuit 23 carries out processing forrecording the edited coded stream ST_(EDIT) supplied from the ECCencoder 20 onto the magnetic tape by overwriting.

Moreover, the system controller 13 controls the recording circuit 23 torecord the system data supplied from the ECC encoder 20 on the basis ofthe recording timing control signal RT_(S) with respect to the systemdata shown in FIG. 10F. That is, processing for recording the systemdata by overwriting advanced by one GOP from the recording timing of thecoded stream is carried out, instead of starting recording of the systemdata at the same timing as that of the coded video stream described inFIG. 10E. In the video tape recorder of the present embodiment, to carryout variable-speed reproduction, identification ID of the preceding GOPand identification ID of the subsequent GOP are recorded as the systemdata.

Since GOP1 consisting of the picture B2 and picture I3′ is rewritten bythis insertion editing, identification ID of GOP1 is changed. Thus, tochange the identification ID of GOP1 described in the system data ofGOP0, overwrite processing for recording the system data is carried outat the timing advanced by one GOP from the recording timing of the codedstream.

In addition, the system controller 13 controls the recording circuit 23to record the audio data supplied from the ECC encoder 20 on the basisof the recording timing control signal RT_(A) with respect to the audiodata shown in FIG. 10G. Since the audio data is not compression-coded,the system delay in the reproduction processing system and the recordingprocessing system is smaller than that of the video data. Therefore, therecording timing of the audio data at IN-point may be equal to therecording timing of the coded video stream.

With reference to FIGS. 11A to 11G, the timing for recording the codedvideo stream, the timing for recording the system data and the timingfor recording the audio data at OUT-point in this insertion editing willnow be described. FIG. 11A shows original data V_(ORG) of the base bandoutputted from the MPEG decoder 29. FIG. 11B shows insertion video dataV_(INS) of the base band to be inserted into the original video dataV_(ORG). FIG. 11C shows edited video data V_(EDIT) of the base bandoutputted from the switching circuit 15. FIG. 11D shows an edited codedstream ST_(EDIT) outputted from the ECC encoder 20. FIG. 11E shows arecording timing control signal RT_(V) for controlling the recordingtiming of the edited coded video stream. FIG. 11F shows a recordingtiming control signal RT_(S) for controlling the recording timing of thesystem data. FIG. 11G shows a recording timing control signal RT_(A) forcontrolling the recording timing of the audio data.

Since FIGS. 11A to 11G are views for explaining the recording timingcontrol signal at OUT-point, the timing of IN-point is not described.

The system controller 13 controls the recording circuit 23 to record theedited coded stream ST_(EDIT) outputted from the ECC encoder 20 onto themagnetic tape on the basis of the recording timing control signalRT_(V). As described with reference to FIGS. 10A to 10G, the systemcontroller 13 does not record all the edited coded streams ST_(EDIT)outputted from the ECC encoder 20 onto the magnetic tape. Actually, thepictures up to OUT-point (i.e., pictures up to the picture I7′) of theinsertion video data are recorded onto the magnetic tape by overwriting,but a picture B10 and a picture I11 of the edited coded stream ST_(EDIT)are not recorded onto the magnetic tape. This is because a picture B10and a picture I11 of the original coded stream ST_(ORG) are alreadyrecorded on the magnetic tape.

Since the picture B10 and picture I11 of the edited coded streamST_(EDIT) are processed by MPEG decoding processing and MPEG re-encodingprocessing, the picture quality of these pictures is slightlydeteriorated from that of the picture B10 and picture I11 of theoriginal coded stream ST_(ORG). Therefore, it is not necessary to recordthe picture B10 and picture I11 of the slightly deteriorated picturequality by overwriting the picture B10 and picture I11 of the originalcoded stream ST_(ORG) of the good picture quality.

However, pictures B8 and I9 of the edited coded stream ST_(EDIT)outputted from the ECC encoder 20 are recorded onto the magnetic tape byoverwriting on the basis of the recording timing control signal RT_(V).This is because the DCT coefficients, coding parameters and quantitiesof generated data of the pictures B8 and I9 of the edited coded streamST_(EDIT) generated by insertion editing are totally different fromthose of the pictures B8 and I9 of the original coded stream ST_(ORG)recorded on the magnetic tape.

The picture B8 of the original coded stream ST_(ORG) is a picturepredictively coded bidirectionally from the picture I7 of the originalcoded stream ST_(ORG) and the picture I9 of the original coded streamST_(ORG). However, as described above, the picture B8 of the editedcoded stream ST_(EDIT) is a picture predictively coded from the pictureI7′ re-encoded by the MPEG encoder 19 and the picture I9 re-encoded bythe MPEG encoder 19.

Therefore, since the picture I7 as a prediction target of the picture B8of the original coded stream ST_(ORG) and the picture I7′ as aprediction target of the picture B8 of the edited coded stream ST_(EDIT)are different from each other, the coding processing result of thepicture B8 of the original coded stream ST_(ORG) and the codingprocessing result of the picture B8 of the edited coded stream ST_(EDIT)are different from each other.

The data quantity obtained by combining the quantity of generated dataof the picture B8 and the quantity of generated data of the picture I9of the original coded stream ST_(ORG) corresponds to the data quantityfor 10 tracks, and the data quantity obtained by combining the quantityof generated data of the picture B8 and the quantity of generated dataof the picture I9 of the edited coded stream ST_(EDIT) corresponds tothe data quantity for 10 tracks. Therefore, the quantity of generateddata of the picture I9 of the edited coded stream ST_(EDIT) generated byre-encoding by the MPEG encoder 19 in insertion editing is differentfrom the quantity of generated data of the picture I9 of the originalcoded stream ST_(ORG) recorded on the magnetic tape.

As described above, the pictures B8 and I9 of the edited coded streamST_(EDIT) generated by insertion editing are different from the picturesB8 and I9 of the original coded stream ST_(ORG) recorded on the magnetictape in terms of the quantity of generated data, the prediction targetpicture and the coding parameter. Therefore, the system controller 13controls the recording circuit 23 to rewrite the pictures B8 and I9 ofthe original coded stream ST_(ORG) recorded on the magnetic tape by thepictures B8 and I9 of the edited coded stream ST_(EDIT) generated byinsertion editing, on the basis of the recording timing control signalRT_(V).

Moreover, the system controller 13 controls the recording circuit 23 torecord the system data supplied from the ECC encoder 20 on the basis ofthe recording timing control signal RT_(S) with respect to the systemdata shown in FIG. 1F. That is, processing for endingoverwrite-recording of the system data delayed by one GOP from therecording timing of the coded stream is carried out, instead of endingrecording of the system data at the same timing as that of the codedvideo stream described in FIG. 11E. In the video tape recorder of thepresent embodiment, to carry out variable-speed reproduction,identification ID of the preceding GOP and identification ID of thesubsequent GOP are recorded as the system data.

Since GOP4 consisting of the picture B8 and picture I9 of the editedcoded stream ST_(EDIT) is rewritten by this insertion editing,identification ID of GOP4 to be recorded as the system data of GOP5 ischanged. Therefore, in order to rewrite the identification ID of GOP4described in the system data of this GOP5, the system controller 13controls the recording circuit 23 to rewrite the system datacorresponding to this GOP on the basis of the recording timing controlsignal RT_(S) with respect to the system data.

In addition, the system controller 13 controls the recording circuit 23to record the audio data supplied from the ECC encoder 20 on the basisof the recording timing control signal RT_(A) with respect to the audiodata shown in FIG. 11G. Since the audio data is not compression-coded,the system delay in the reproduction processing system and the recordingprocessing system is smaller than that of the video data. Therefore, therecording timing of the audio data at OUT-point may be equal to therecording timing of the coded video stream.

With the above-described structure, with respect to the video signalsnear IN-point and OUT-point, coded data is generated by joining thevideo signals reproduced from the magnetic tape to the edited videosignals, and the coded data is rerecorded onto the magnetic tape, ifnecessary. In this manner, even when IN-point and OUT-point are set atvarious points based on the frame as a unit, correctly coded videosignals can be recorded onto the magnetic tape. Thus, editing processingbased on the frame as a unit can be freely carried out.

In the above-described embodiment, coding is carried out so that GOPconsisting of I-picture and B-picture has a constant data quantity.However, this invention is not limited to this embodiment and may bebroadly applied to the case where the quantity of generated data is notlimited. In this case, too, editing processing based on the frame unitcan be carried out by reproducing video signals already recorded on themagnetic tape only with respect to the frames necessary for correctcoding processing, as described above.

In addition, in the above-described embodiment, insertion editing iscarried out by reproducing video signals by two pairs of advancedreading heads. However, this invention is not limited to this embodimentand may be broadly applied to the case where insertion editing iscarried out by reproducing video signals by one pair of advanced readingheads.

Also, in the above-described embodiment, video signals arecompression-coded by the technique in conformity to the MPEG standard.However, this invention is not limited to this embodiment and may bebroadly applied to the case where data compression coding is carried outby utilizing correlation between frames.

In addition, in the above-described embodiment, video signals arerecorded onto the magnetic tape. However, this invention is not limitedto this embodiment and may be broadly applied to the case where videosignals are continuously or discretely recorded onto various recordingmedia such as optical discs.

As described above, according to the data recording device and the dataediting device of the present invention, an original coded streamreproduced from the magnetic tape is temporarily decoded to restorevideo data of the base band, and original video data and insertion videodata are connected to each other in the state of base band video.Therefore, insertion editing based on the frame unit can be carried outin accordance with arbitrarily set edit points.

Also, instead of recording all the edited coded streams generated bycoding edited video data edited at the base band level onto the magnetictape, pictures corresponding to insertion video data and pictures nearedit points such as IN-point and OUT-point, from among the edited codedstream, are recorded by overwriting at positions corresponding to thepictures of the original coded stream recorded on the recording medium.In short, only the pictures of the edited coded stream having codingresults changed by insertion editing processing are recorded byoverwriting onto the magnetic tape. Therefore, deterioration in picturequality of the coded stream which is insertion-edited and rerecorded onthe magnetic tape can be minimized.

In addition, according to the data recording device and the data editingdevice of the present invention, if a picture of the edited coded streamis affected by insertion editing processing and is different from apicture of the original coded stream recorded on the magnetic tape, thepicture of the edited coded stream is recorded onto the magnetic tape byoverwriting. If the picture of the edited coded stream is not affectedby insertion editing processing and is the same as the picture of theoriginal coded stream recorded on the magnetic tape, the picture of theedited coded stream is not recorded onto the magnetic tape. Therefore,even when insertion editing processing is carried out on the framebasis, deterioration in picture quality of the coded stream which isinsertion-edited and rerecorded on the magnetic tape can be prevented.

Also, according to the data recording device and the data editing deviceof the present invention, if the picture immediately before IN-point isI-picture, overwrite recording is started so that pictures from thepicture immediately after IN-point are recorded onto the magnetic tapeby overwriting. If the picture immediately before IN-point is B-picture,overwrite recording is started so that pictures at least from B-pictureas the picture immediately before IN-point are recorded onto themagnetic tape. Therefore, the picture quality of the coded stream whichis insertion-edited and recorded on the magnetic tape is notdeteriorated, and the picture quality of decoded images is notdeteriorated, either.

In the foregoing description, the coding method employed by the MPEGencoder 19 for insertion editing is a particular compression codingmethod using the BIBI . . . pattern. However, the present invention isnot limited to such particular compression coding method and may also beapplied to other general compression coding methods. An example ofinsertion editing by using a general compression coding method will nowbe described with reference to FIGS. 12A to 12E and FIGS. 13A to 13E.

FIGS. 12A to 12E illustrate processing at IN-point in the case whereinsertion editing is carried out with respect to a general coded streamwhich is compression-coded for each 15 pictures as one GOP. FIG. 12Ashows original video data V_(ORG) reproduced from the recording medium.FIG. 12B shows insertion video data V_(INS). FIG. 12C shows edited videodata V_(EDIT) generated by insertion-editing the insertion video dataV_(INS) into the original video data V_(ORG). FIG. 12D shows an editedcoded stream ST_(EDIT) obtained by MPEG-coding the edited video data.FIG. 12E shows a recording timing control signal RT_(V) indicating therecording timing for recording the edited coded stream ST_(EDIT) ontothe recording medium by overwriting.

As indicated by arrows in FIG. 12D, a picture B9 immediately beforeIN-point in the edited coded stream ST_(EDIT) is predictively coded froma picture P8 and a picture P11′. Therefore, the picture B9 of the editedcoded stream ST_(EDIT) and a picture B9 of the original coded streamST_(ORG) recorded on the recording medium are different from each other.Thus, the system controller 13 controls the recording circuit 23 tostart overwrite recording with the picture B9 immediately beforeIN-point in the edited coded stream ST_(EDIT).

In the above-described example, IN-point is set between the picture P8and the picture B9. Also, in the case where IN-point is set between thepicture B9 and the picture B10 and in the case where IN-point is setbetween the picture B10 and the picture P11, overwrite recording issimilarly started with the picture B9 immediately before IN-point in theedited coded stream ST_(EDIT).

FIGS. 13A to 13E illustrate processing at OUT-point in the case whereinsertion editing is carried out with respect to a general coded streamwhich is compression-coded for each 15 pictures as one GOP. FIG. 13Ashows original video data V_(ORG) reproduced from the recording medium.FIG. 13B shows insertion video data V_(INS) FIG. 13C shows edited videodata V_(EDIT) generated by insertion-editing the insertion video dataV_(INS) into the original video data V_(ORG). FIG. 13D shows an editedcoded stream ST_(EDIT) obtained by MPEG-coding the edited video data.FIG. 13E shows a recording timing control signal RT_(V) indicating therecording timing for recording the edited coded stream ST_(EDIT) ontothe recording medium by overwriting.

As indicated by arrows in FIG. 13D, a picture P8 of the edited codedstream ST_(EDIT) is a picture predictively coded from a picture P5′. Apicture P11 is a picture predictively coded from the picture P8. Apicture P14 is a picture predictively coded from the picture P11. Apicture B7 is a picture predictively coded from a picture B6′ and thepicture B8. A picture B9 and a picture B10 are pictures predictivelycoded from the picture P8 and the picture P11. A picture B12 and apicture B13 are pictures predictively coded from the picture P11 and thepicture P14.

In short, all the pictures from the picture B7 to the picture P14 in theedited coded stream ST_(EDIT) are affected by the picture P5′ generatedfrom the insertion video data V_(INS). Therefore, the pictures from thepicture B7 to the picture P14 in the edited coded stream ST_(EDIT) aredifferent from the pictures from the picture B7 to the picture P14 inthe original coded stream ST_(ORG).

Thus, the system controller 13 controls the recording circuit 23 to endoverwrite recording at the end (picture P14) of the edited coded streamST_(EDIT) on the basis of the recording timing control signal RT_(V).

In the above-described embodiment, coding processing is carried out foreach 15 pictures as one GOP. However, this invention is not limited tothis embodiment, and editing processing on the frame basis can becarried out, no matter what number of pictures are included in one GOP.Also, in the above-described embodiment, video signals arecompression-coded by the technique in conformity to the MPEG standard.However, this invention is not limited to this embodiment and may bebroadly applied to the case where data compression coding is carried outby utilizing correlation between frames.

As described above, according to the present invention, by generatingcoded data to be reproduced, decoded and recorded with respect to theframe immediately before IN-point and the frame immediately afterOUT-point, and if necessary, rerecording the coded data onto therecording medium, insertion editing processing on the frame basis can becarried out even in the case where image signals are recorded byinter-frame coding processing.

As described above, according to the data recording device and the dataediting device of the present invention, an original coded streamreproduced from the magnetic tape is decoded to restore video data ofthe base band, and the original video data and insertion video data areconnected to each other in the state of base band video. Thus, insertionediting on the frame basis can be carried out.

Also, instead of recording all the edited coded streams generated bycoding edited video data edited at the base band level onto the magnetictape, pictures corresponding to insertion video data and pictures nearedit points such as IN-point and OUT-point, from among the edited codedstream, are recorded by overwriting at positions corresponding to thepictures of the original coded stream recorded on the recording medium.In short, only the pictures of the edited coded stream having codingresults changed by insertion editing processing are recorded byoverwriting onto the magnetic tape. Therefore, deterioration in picturequality of the coded stream which is insertion-edited and rerecorded onthe magnetic tape can be minimized.

In addition, according to the data recording device and the data editingdevice of the present invention, if OUT-point is set in a GOP, the codedstream of the GOP including OUT-point is rewritten onto the magnetictape. Therefore, deterioration in picture quality near OUT-point can beprevented.

Also, according to the data recording device and the data editing deviceof the present invention, if a picture of the edited coded stream isaffected by insertion editing processing and is different from a pictureof the original coded stream recorded on the magnetic tape, the pictureof the edited coded stream is recorded onto the magnetic tape byoverwriting. If the picture of the edited coded stream is not affectedby insertion editing processing and is the same as the picture of theoriginal coded stream recorded on the magnetic tape, the picture of theedited coded stream is not recorded onto the magnetic tape. Therefore,even when insertion editing processing is carried out, deterioration inpicture quality of the coded stream which is insertion-edited andrerecorded on the magnetic tape can be prevented.

Also, according to the data recording device and the data editing deviceof the present invention, if the picture immediately before IN-point isI-picture, overwrite recording is started so that pictures from thepicture immediately after IN-point are recorded onto the magnetic tapeby overwriting. If the picture immediately before IN-point is B-picture,overwrite recording is started so that pictures at least from B-pictureas the picture immediately before IN-point are recorded onto themagnetic tape. Therefore, the picture quality of the coded stream whichis insertion-edited and recorded on the magnetic tape is notdeteriorated.

1. A data recording device for recording a coded stream onto a recordingmedium, the device comprising: reproducing means for reproducing anoriginal coded stream recorded on the recording medium; decoding meansfor decoding the original coded stream outputted from the reproducingmeans and generating decoded video data of a base band; editing meansfor switching the decoded video data of the base band and insertionvideo data at a set edit point and generating edited video data; codingmeans for coding the edited video data to generate an edited codedstream; recording means for recording the edited coded stream onto therecording medium; and control means for controlling the recording meansto record a picture of the edited coded stream onto the recording mediumby overwriting in the case where the picture of the edited coded streamis affected by editing processing by the editing means and is differentfrom a picture of the original coded stream recorded on the recordingmedium, and not to record the picture of the edited coded stream ontothe recording medium in the case where the picture of the edited codedstream is not affected by editing processing by the editing means and isthe same as the picture of the original coded stream recorded on therecording medium.
 2. The data recording device as claimed in claim 1,wherein the control means generates a recording timing control signalfor controlling recording operation for recording the edited codedstream onto the recording medium, the recording means controllingrecording operation for recording the coded stream onto the recordingmedium on the basis of the recording timing control signal.
 3. The datarecording device as claimed in claim 1, wherein the recording means hasmeans for recording audio data and system data corresponding to thecoded stream to be recorded onto the recording medium into apredetermined area on the recording medium together with the codedstream, the control means generating a recording timing control signalfor controlling overwrite recording of the edited coded stream onto therecording medium, a recording timing control signal for controllingrecording of the system data onto the recording medium, and a recordingtiming control signal for controlling recording of the audio data ontothe recording medium, the recording means controlling recordingoperation for recording the edited coded stream onto the recordingmedium on the basis of the recording timing control signal with respectto the edited coded stream, the recording means controlling recordingoperation for recording the system data onto the recording medium on thebasis of the recording timing control signal with respect to the systemdata, the recording means controlling recording operation for recordingthe audio data onto the recording medium on the basis of the recordingtiming control signal with respect to the audio data.
 4. The datarecording device as claimed in claim 1, wherein the recording medium isconstituted by a magnetic tape, the recording means having a recordinghead for recording the coded stream onto the magnetic tape, thereproducing means having a reproducing head for reproducing the originalcoded stream recorded on the magnetic tape, the reproducing head beingprovided at a position advanced from the recording head by an amountcorresponding to a system delay based on decoding processing of thedecoding means and coding processing of the coding means.
 5. The datarecording device as claimed in claim 1, wherein the recording medium isconstituted by a magnetic tape, the recording means having a recordinghead for recording the coded stream onto the magnetic tape, thereproducing means having a reproducing head for reproducing the originalcoded stream recorded on the magnetic tape, the reproducing head beingprovided at a position advanced from the recording head so that whenoriginal data reproduced from the magnetic tape by the reproducing headof the reproducing means is supplied to the recording means through thedecoding means and the coding means and is newly recorded by overwritingonto the recording medium by the recording head of the recording means,the position where the reproduced original data is recorded on themagnetic tape and the position of the data newly recorded by overwritingon the magnetic tape by the recording head are coincident with eachother.
 6. The data recording device as claimed in claim 1, wherein therecording medium is constituted by a magnetic tape, the recording meanshaving a recording head for recording the coded stream onto the magnetictape, the reproducing means having a reproducing head for reproducingthe original coded stream recorded on the magnetic tape, the recordinghead and the reproducing head being arranged so that the reproducinghead scans the magnetic tape earlier than the recording head by anamount of a delay time obtained by adding a delay time of a reproductionprocessing system including decoding processing of the decoding meansand a delay time of a recording processing system including codingprocessing of the coding means.
 7. The data recording device as claimedin claim 4, wherein the reproducing head is constituted by a pluralityof magnetic heads, the reproducing means generating a reproduced codedstream by synthesizing reproduced signals from the plurality of magneticheads even when the plurality of magnetic heads are in off-track stateswith respect to tracks on the magnetic tape.
 8. The data recordingdevice as claimed in claim 1, wherein the control means controls therecording means to record pictures from a picture immediately afterIN-point onto the recording medium by overwriting if a pictureimmediately before IN-point is I-picture, and controls the recordingmeans to record picture at least from B-picture as a picture immediatelybefore IN-point onto the recording medium by overwriting if the pictureimmediately before IN-point is B-picture.
 9. The data recording deviceas claimed in claim 1, wherein the control means controls the recordingmeans so that if OUT-point is set in a GOP, at least pictures up to thelast picture of the GOP having OUT-point set therein are recorded byoverwriting onto the recording medium.
 10. A data recording device forrecording a coded stream onto a recording medium, the device comprising:reproducing means for reproducing an original coded stream recorded onthe recording medium; decoding means for decoding the original codedstream outputted from the reproducing means and generating decoded videodata of a base band; editing means for switching the decoded video dataof the base band and insertion video data at a set edit point andgenerating edited video data, coding means for coding the edited videodata to generate an edited coded stream; recording means for recordingthe edited coded stream onto the recording medium; and control means forcontrolling the recording means to record pictures from a pictureimmediately after IN-point onto the recording medium by overwriting inthe case where a picture immediately before the IN-point is I-picture,and controlling the recording means to record pictures at least fromB-picture as a picture immediately before the IN-point onto therecording medium by overwriting in the case where the pictureimmediately before the IN-point is B-picture.
 11. The data recordingdevice as claimed in claim 10, wherein the control means controls therecording means so that if OUT-point is set in a GOP, at least picturesup to the last picture of the GOP having OUT-point set therein arerecorded by overwriting onto the recording medium.